1. Field of the Invention
The present invention relates to a lens barrier unit for protecting an image pickup lens, and an image capturing apparatus provided with the lens barrier unit.
2. Description of the Related Art
Image capturing apparatuses such as a digital video camera, a digital still camera, and the like form an image of a subject by an image pickup lens and pick up the image of the subject by an image pickup element arranged behind the image pickup lens. As the image pickup element, a CCD image sensor (Charge Coupled Device Image Sensor), CMOS (Complementary Metal Oxide Semiconductor) image sensor, and the like can be cited, for example. In the recent image capturing apparatuses, a lens barrier mechanism is provided in front of the image pickup lens in order to prevent damage on the image pickup lens and to protect the same.
The lens barrier mechanism opens an optical path and allows a light beam to enter the image pickup lens when shooting and closes the optical path so as to protect the image pickup lens when not shooting. As the lens barrier mechanism, there is known a lens barrier mechanism of a four-blade rotationally movement type in which four lens barrier members 1a, 1b, 1c, and 1d are pivotally moved so that the optical path in front of the image pickup lens 2 can be opened/closed as shown in FIG. 6, for example (see Japanese Laid-Open Patent Publication (Kokai) No. 2002-148682, for example).
However, the lens barrier mechanism in the above-described prior-art technology includes a base member of a ring shape having shafts 3a and 3b at symmetrical positions, the shaft 3a pivotally supporting the lens barrier members 1a and 1b, while the shaft 3b pivotally supporting another lens barrier members 1c and 1d. The above-described technology is configured such that the optical path of an image pickup lens 2 is opened/closed by pivotally moving the four lens barrier members 1a to 1d, which requires to provide a space, in which a shaft for pivotally supporting the respective lens barrier members is installed, at each of the symmetrical positions of the ring-shaped base member, and further requires to provide retreat spaces, to which the lens barrier members 1a to 1d are retreated, in order to open the optical path by pivotally moving the four lens barrier members 1a to 1d. As a result, the lens barrier mechanism itself becomes considerably greater in diameter than the image pickup lens, which provides a problem that a demand for size reduction of the entire image capturing apparatus cannot be met, and moreover no measure is taken against deformation or the like of the lens barrier mechanism when an external force acts thereto, which provides a problem that the external force-resistance is not sufficient.